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In this paper studies on the lab formulated fritless silver thick film paste with two different binder compositions that have been used to fabricate λ/2 microstrip rejection filter in the X and Ku band are reported. These have been compared with ESL (USA) paste and copper thin film metallization for the same circuit. The thick film circuits were overlayed with TiO₂ thick film of different thickness and changes in the characteristics studied. In the X band, the Q of the filter improves with overlay and is also dependent on the Ag paste formulation, whereas in the Ku band there are no thick film paste dependent properties observed due to overlay. Thickness of overlay and metallization paste formulation dependent factors should be taken into consideration during fabrication of high density and multi‐layer microwave integrated circuits.

The purpose of this paper is to investigate and report the impact of glass frit variation in silver thick film pastes used as surface conductors in low temperature co‐fired ceramics technology (LTCC), especially on the properties such as warpage of LTCC associated with conductors, microstructure of the fired thick films, sheet resistance and adhesion on LTCC.

Silver thick film paste compositions were formulated by changing the silver glass frit ratio. The compatibility of these formulated paste compositions with LTCC (DP 951AX) substrate were evaluated. The properties such as microstructure developments, the change in sheet resistance, warpage of LTCC substrate with respect to glass frit ratio of the developed silver films on LTCC were evaluated.

The results reveal that the glass frit percentage used in paste formulation is equally responsible for the disturbance in the properties such as microstructure, warping and electrical properties of the fired thick films on LTCC. It was observed that the paste composition, in particular sample SP10B containing the highest glass frit percentage, is compatible with the LTCC tape under processing conditions. The sheet resistance value in the range of 5 mΩ/□ and the fired films showed very good adhesion (3.95 N), irrespective of the glass frit composition.

The paper provides useful evaluations of properties such as microstructure developments, changes in sheet resistance and warpage of LTCC substrate with respect to glass frit ratio of the developed silver pastes on LTCC.

The realization of thick‐film circuits on glass substrates is discussed. Within the large number of commercially available thick‐film pastes, suitable pastes for thick‐film conductors, resistors and dielectrics on glass substrates have been found. Experimental results for these pastes are presented. Finally two applications for thick‐film on glass technology are demonstrated.

In various publications noble steel is mentioned as a possibility for use as a substrate in thick film technology processing. The possibility to cut, stencil and drill steel sheets to desired shapes and the attractive price difference compared with alumina as well as PC board materials justified an investigation. A variety of steel sheets in various formulations from various vendors is offered on the market as well as ceramic pastes for thick film applications. This investigation aims to find out the most suitable ceramic paste for coating steel substrates in a common thick film process.

This paper outlines methods and results of wetting, leaching and adhesion analyses on copper thick film conductors over alumina and multilayer glasses after different processing conditions. The intention is to provide a better background for evaluating and optimising materials and processing conditions in copper thick films and working out quick, reliable and quantitative methods for better characterisation of copper conductors in production. For these reasons the following methods were used: (a) wetting and leaching analyses with a scanning wetting balance, working in nitrogen, (b) pull tests with solder contacts on copper thick film conductors after soldering, ageing and thermal cycling, and (c) some additional surface analyses (REM, EDX, Auger) for a better understanding of copper pastes and their material interactions, when processed under different conditions. The results are summarised under three general aspects: surface structure and wetting of copper thick films, wetting and leaching of various copper thick films after different processing conditions, and finally the influence of different wetting properties of such surfaces on the solder adhesion strength after soldering, ageing and thermal cycling. The results give good insight into the various interactions of copper thick films with their substrate materials and confirm the ability of the described wetting and leaching analyses for these purposes.

The purpose of this paper is to ascertain chemical changes occurring at various stages involved in processing of silver‐based photoimageable thick films; and to determine ensuing topographical features which other wise appeared to be hindered in 2D scanning electron microscopy.

Surface sensitive techniques, viz. X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used.

Interfacial adhesion of silver film with substrate (Al₂O₃) was specifically looked into with respect to role played by photoimaging (before and after exposure to ultra‐violet light). XPS results revealed occurrence of subtle chemical changes in terms of unsaturation to saturation in C−C bonding and also an interesting C−Al bonding which presumably improves mechanical adhesion of unfired film with the alumina substrate. AFM was carried out to examine the surface roughness, particle size, and microstructure of film which are very important from the standpoint of high‐frequency applications.

Surface sensitive techniques like XPS and AFM were exclusively used in order to characterize silver‐based photoimageable thick films.

This paper reports the results of development work conducted on nitrogen‐based atmospheres in order to improve the firing of copper thick film systems through continuous furnaces. The proposed solution is particularly suitable for industrial production conditions since it allows variations of the material quantity processed per unit time, resulting not only in an improvement in quality but also in productivity. Such improvements have been achieved by using a new gas distribution system which provides both zone control and regulation of oxygen additions in the nitrogen furnace atmosphere. An efficient set‐up of this system has become possible thanks to precise control of the oxygen profile in relation to the temperature cycle, taking into account various inks' characterisation, and owing to an extensive study of the effects of oxygen additions on copper thick film properties. The solution was tested in a muffle‐lined belt furnace with several commercial dielectric and copper inks, and for increasing oxygen additions into the furnace preheat zone. Different sample patterns were designed to test both monolayer and multilayer systems. The test programme includes measurements of resistivity, bondability, solderability, dielectric breakdown voltage and adhesion of copper films on alumina and on dielectric layers before and after ageing. Ink characterisation by thermogravimetry and by several gas analyses has confirmed that the organic vehicle removal mechanism under nitrogen atmospheres doped with oxygen is a burnout. Indeed, significant oxygen consumption occurs within the temperature range of the removal, as a function of the amount of ink processed. Oxygen additions in the furnace burnout zone greatly improve both the dielectric breakdown voltage and the adhesion of copper on alumina and on dielectric (especially after ageing), while sheet resistivity, wire bondability and soft solderability are not altered below a defined O2 level. It is therefore possible to determine an optimum oxygen addition range for which the thick films fired under such conditions will have the best characteristics. This optimum oxygen window is achieved thanks to a new regulation system which operates whenever variations occur in the quantity of paste processed.

Different techniques applied for the fabrication of thick‐film fine lines have been analysed. The basics, achievements, advantages and disadvantages of improved screen printing, screen printing with metal masks, the direct writing method, offset printing and photoformed or photoetched thick‐film are presented. In addition, current trends in front metallisation of silicon solar cells are described. Based on a critical review, the use of thick‐film fine lines for this purpose is discussed.

The purpose of this paper is to present the properties of thick-film resistors made of novel pastes prepared from glass and graphite.

Graphite-based resistors were made of thick-film pastes with different graphite-to-glass mass fraction were prepared and examined. Sheet resistance, temperature coefficient of resistance, impact of humidity and short-term overload were investigated. The properties of the layers fired in atmospheres of air at 550°C and nitrogen at 875°C were compared.

Graphite-based resistors with various graphite-to-glass ratios made possible to obtain a wide range of sheet resistance from single O/square to few kO/square. These values were dependent on firing atmosphere, paste composition and the number of screen-printed layers. The samples made of paste with 1:1 graphite-to-glass ratio exhibited the temperature coefficient of resistance of about −1,000 ppm/°C, almost independently on the firing atmosphere and presence of a top coating. The resistors fired in the air after coating with overglaze, exhibited significantly lower sheet resistance, reduced impact of humidity and improved power capabilities.

In this paper, graphite-based resistors for applications in typical high-temperature cermet thick-film circuits were presented, whereas typical graphite-based resistors were fabricated in polymer thick-film technology. Owing to very low cost of the graphite, the material is suitable for low-power passive circuits, where components are not subjected into high temperature, above the typical temperature of operation of standard electronic components.

The paper aims to focus on thick film planar thermistors.

Thick film planar thermistors such as rectangular, sandwich, multilayer, segmented and interdigitated were printed of law temperature NTC paste called NTC 3K3 95/2 (Ei Iritel). Their resistivity was measured at room temperature as a function of volume resistivity variations due to electrode effect (diffusion of PdAg into NTC layer) and variation of geometrical parameters such as length l, width w, thickness d, number of segments n. The experimental data obtained were used in forming a model by the simple fitting procedure for counting diffusion effect on volume resistivity and resistivity dependence on geometrical parameters.

Thermal behavior of NTC thick films was measured in the range of −30‐120°C. Exponential factor B was fitted for measured values and included in the proposed thick film thermistors model. The agreement of measured and calculated data enables simulation of new thermistor geometries.

The paper focuses on the experiment which was the first step in forming a total physical/mathematical model proposed for thick film thermistor resistivity.